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Inches to MM Live Converter

Inches to MM Live Converter

Inches to MM Converter

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Tip: type inches as 0.5, 3/8 or 1 1/4, or tap a preset. Several values (new line, space or semicolon) also work.
Output appears here
 

Example 1: Convert 0.5 Inches to MM

StepCalculationResult
1. Inches as a decimal0.5 in0.5 in
2. Multiply by 25.40.5 x 25.412.7 mm
3. RoundTo 3 decimals12.700 mm
4. CentimetersInches x 2.541.2700 cm
0.5 in = 12.700 mm = 1.2700 cm.

Example 2: Convert 3/8 Inch to MM

StepCalculationResult
1. Inches as a decimal3/8 in0.375 in
2. Multiply by 25.40.375 x 25.49.525 mm
3. RoundTo 3 decimals9.525 mm
4. CentimetersInches x 2.540.9525 cm
3/8 in = 0.375 in = 9.525 mm = 0.9525 cm.

SAE Socket & Hardware Sizing Chart (Inches to MM)

Imperial FractionDecimal InchesMillimeters (mm)
1/16"0.06251.5875
1/8"0.12503.175
1/4"0.25006.350
3/8"0.37509.525
1/2"0.500012.700
3/4"0.750019.050
1"1.000025.400

Fractional Inches to MM (1/16 to 2 inches)

Imperial FractionDecimal InchesMillimeters (mm)Centimeters (cm)
1/160.06251.58750.15875
1/80.12503.17500.31750
3/160.18754.76250.47625
1/40.25006.35000.63500
5/160.31257.93750.79375
3/80.37509.52500.95250
7/160.437511.11251.11125
1/20.500012.70001.27000
9/160.562514.28751.42875
5/80.625015.87501.58750
11/160.687517.46251.74625
3/40.750019.05001.90500
13/160.812520.63752.06375
7/80.875022.22502.22250
15/160.937523.81252.38125
11.000025.40002.54000
1 1/161.062526.98752.69875
1 1/81.125028.57502.85750
1 3/161.187530.16253.01625
1 1/41.250031.75003.17500
1 5/161.312533.33753.33375
1 3/81.375034.92503.49250
1 7/161.437536.51253.65125
1 1/21.500038.10003.81000
1 9/161.562539.68753.96875
1 5/81.625041.27504.12750
1 11/161.687542.86254.28625
1 3/41.750044.45004.44500
1 13/161.812546.03754.60375
1 7/81.875047.62504.76250
1 15/161.937549.21254.92125
22.000050.80005.08000

SAE Sizes and Nearest Whole Millimeter

Imperial FractionDecimal InchesMillimeters (mm)Nearest Whole mm
5/160.31257.93758
3/80.37509.52510
7/160.437511.112511
1/20.500012.70013
9/160.562514.287514
5/80.625015.87516
11/160.687517.462517
3/40.750019.05019
13/160.812520.637521
7/80.875022.22522
15/160.937523.812524
11.000025.40025
1 1/161.062526.987527
1 1/81.125028.57529
1 1/41.250031.75032

Common Inches in MM and CM

InchesMillimeters (mm)Centimeters (cm)
0.0010.02540.00254
0.0050.12700.01270
0.010.25400.02540
0.020.50800.05080
0.030.76200.07620
0.1253.17500.31750
0.256.35000.63500
0.512.70001.27000
0.7519.05001.90500
125.40002.54000
1.538.10003.81000
250.80005.08000
376.20007.62000
4101.600010.16000
6152.400015.24000
12304.800030.48000
24609.600060.96000
36914.400091.44000

Common Sizes in Inches and MM

ObjectInchesMillimeters (mm)Centimeters (cm)
Standard ruler12304.800030.48000
Yardstick36914.400091.44000
US Letter paper width8 1/2215.900021.59000
US Letter paper length11279.400027.94000
US Legal paper length14355.600035.56000
2x4 lumber, actual thickness1 1/238.10003.81000
2x4 lumber, actual width3 1/288.90008.89000
Nominal 3/4 in plywood (actual 23/32 in)23/3218.25631.82563
Nominal 1/2 in plywood (actual 15/32 in)15/3211.90631.19063
Standard drywall thickness1/212.70001.27000
US dollar bill length6.14155.956015.59560
Standard door thickness1 3/834.92503.49250

Technical Q&A / FAQ Matrix

Technical Developer QuestionExact Solution & Code Snippet
How do I convert inches to mm in JavaScript?(0.5 * 25.4).toFixed(3) // 12.700
How do I convert inches to mm in Python?round(0.5 * 25.4, 3)
How do I convert inches to mm in Go?fmt.Printf("%.3f", 0.5*25.4)
How do I convert inches to mm in Java?String.format("%.3f", 0.5 * 25.4)
How do I convert inches to mm in C#?(0.5 * 25.4).ToString("F3")
How do I convert inches to mm in PHP?echo round(0.5 * 25.4, 3);
How do I convert inches to mm in Rust?format!("{:.3}", 0.5 * 25.4)
How do I convert inches to mm on Linux?awk 'BEGIN { printf "%.3f\n", 0.5 * 25.4 }'
How do I convert a mixed fraction like 5 3/8 inches to mm in JavaScript?const toMm = (w, n = 0, d = 1) => ((w + n / d) * 25.4).toFixed(3); // toMm(5, 3, 8) = 136.525
How do I convert a mixed fraction to mm in Python?from fractions import Fraction; print(float(Fraction(43, 8) * Fraction(254, 10))) # 5 3/8 in = 136.525
How do I convert inches to mm by hand?Multiply the inches by 25.4. 0.5 x 25.4 = 12.7 mm. For a fraction, divide first: 3/8 = 0.375 and 0.375 x 25.4 = 9.525 mm.
Why do I multiply by 25.4?The inch is defined as exactly 25.4 millimeters (2.54 cm), so the factor is exact, not rounded.
Can I swap SAE and metric sockets?Not safely. 1/2 in is 12.7 mm and the nearest metric size is 13 mm, so the fit is loose and can round off the fastener head. Use the exact size.
How many mm is one thousandth of an inch (1 thou)?0.0254 mm, because 0.001 x 25.4 = 0.0254.
How do I convert a fraction of an inch to a decimal?Divide the top number by the bottom number. For 5/16: 5 / 16 = 0.3125 in, which is 7.9375 mm.
How do I convert mm back to inches?Divide by 25.4. For example 12.7 mm / 25.4 = 0.5 in.

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